Pedro Razquin, CEO of Zeulab, said the presence of antibiotics in food has been a concern for years.
“Antimicrobials have made a major contribution to improving animal health and welfare for decades. However, due to the wide use of antibiotics other than for disease treatment, the amount of antimicrobials used in animal production has increased considerably in the last 10 years.
“The misuse and overuse of these drugs in humans and animal production has led to antibiotic-resistant bacteria. Common antibiotics are not effective against those resistant bacteria and so, bacterial infections have become harder to treat.”
Impact of misuse
Razquin said the impact of misuse of antibiotics is a great social, economic and technological burden for the EU as antibiotic resistance leads to longer hospital stays, higher medical costs and increased mortality.
Antibiotic resistance causes 25,000 deaths in the EU every year (OCU, 2013) and 23,000 in USA (CDC, 2013).
Food contaminated with antibiotics leads to high industrial losses due to meat or milk destroyed by incineration and technological problems for companies manufacturing fermented foods such as cheese and yogurt.
“Antibiotics are extensively monitored in the dairy sector as they are included in the payment criteria in many countries and because antibiotics interfere in the production of fermented product such us yogurt or cheese,” said Razquin.
Commission Regulation (EC) No. 37/2010 established the maximum residue limits (MRL) for different antibiotic residues and sulfonamides for different food matrices.
Examples are: 4ppb for Penicillin G, Ampillicin and Amocillicin, 100 ppb for sulfonamides or tetracycline groups.
Razquin said analysis of antibiotics in food is usually done by screening methods as there are a large number of drugs to be monitored.
“Post-screening and confirmatory methods can also be used in further analyses to identify the antibiotic group or the particular residue present in food; as well as the amount of the drug found,” he said.
“Microbial methods, based on the bacteria inhibition growth, are used as a first step of screening. These methods are cost effective and detect more than 40 residues with qualitative results but the antibiotic present is not identified.
“Immunochemical, enzymatic or chromatography methods that target a specific antibiotic or groups of them are further used to identify the residues present in food.”
Testing antibiotic residues in food
The traditional ‘five plate method’ is still used as a reference method but is time consuming and requires laboratory facilities and technical skills, said Zeulab.
Commercial microbial ready-to-use tests, such as the firms’ Eclipse or Explorer systems, are widely available and commonly used as they are faster and easier to perform.
These methods are based on Geobacillus stearothermophilus and use a pH colour indicator.
The user has to decide, based on the colour and in comparison to a negative control sample, if results are positive of negative.
However, this could be difficult when antibiotics are close to the Limit of Detection of the test and can vary depending on the person viewing the results.
The firm’s e-Reader for antibiotics detection enables multi-screening of more than 30 antibiotics in milk and meat.
It performs the microbial test (Eclipse or Explorer) incubating at 65 °C and monitoring the colour in real time to calculate the bacteria growth.
After the sample is added results can be viewed three hours later. Numerical results are displayed on the screen and saved in an internal memory for traceability.
This system uses software to integrate time and colour parameters to determine the endpoint of the assay, stopping automatically and interpreting qualitative results.
E-Reader can be used for daily checks by farmers, food processors and retailers.